Tooth color approximating system

ABSTRACT

A dental color matching system. A series of translucent films are printed with a variety of colors that closely approximate the colors found in human teeth. The films, or sections of the films, may be reversibly self-adhesive for ease in placing on and removing from a template, or on top of one another, in a sequence until the desired or matching color is obtained. The color is communicated among dental professionals and patient, for example, by indicia that encode the different colors found in a shade system used by dental professionals or in the tooth itself. By using the invention, a dental professional can thus economically and efficiently prepare a dental prosthesis with a color that closely matches that of a patient&#39;s natural tooth.

RELATED APPLICATION

[0001] This application is a Continuation of application Ser. No.10/034,868, filed on Dec. 27, 2001, which is expressly incorporated byreference herein.

FIELD OF THE INVENTION

[0002] The invention relates to a method and apparatus to improveapproximation of the color of teeth and communication of this color.

BACKGROUND OF THE INVENTION

[0003] The recent development of dental porcelain allows a skilleddental technician to produce a dental prosthesis that closelyapproximates the natural state, if provided with accurate information ofthe color of a tooth (or teeth) to be restored. To produce a lifelikedental prosthesis, such as a crown, bridge, etc., dental professionalsmust communicate among themselves and to patients the often subtledifferences in color that are found in human teeth. When formulating theprosthesis, it is important that dentists, dental technicians, andpatients refer to the same color.

[0004] One of the most commonly used devices to match tooth color hasbeen the dental shade guide. The shade guide, usually made of porcelainor plastic, is commercially available under names such as Vita-Lumin™(Vita), Bioform™ (Dentsply), and Vitapan 3-D Master™ (Vita).

[0005] Such commercial color guides, however, have limited use forseveral reasons. One reason is that the colors in the guides are notable to match the subtle differences of the colors found in human teeth.Another reason is that the shade guides are grouped in terms of chroma,hue, and value on the basis of the Munsell Chromatic Scale. A dentalprofessional is forced to describe tooth color, which is not a logicalsystem, by a logical system consisting of a letter, a number, or bothtogether. A third reason is that the porcelains or plastics used to makethe shade guides are of different quality from the porcelains used bydental professionals in fabricating the prosthesis. The resultingproduct is frequently of a different color than that of the naturaltooth of a patient. Even if the color is closely matched, the subtledifferences of individual tooth/teeth color(s) resulting from differentvalues are often ignored or compromised. This diminishes the aestheticappearance of the prosthesis.

[0006] To overcome the problems which accompany the use of commercialshade guides, there have been attempts by dental professionals toproduce custom-made shade guides for their own use. Several coloredsamples of plastic, porcelain, or other materials are usually made tomatch the various colors of different parts of an individual tooth. Thismethod, however, is very expensive, time-consuming, and the results arenot always satisfactory. To remedy the situation, extrinsicmodifications of commercial dental color guides also have beenattempted. For example, gray plastic or porcelain facets have been madewhich adapt to an individual shade tab of a shade or color guide tomatch the value of a tooth, that is, its translucent grayness. This isdescribed by Ubassy in Shape and Color. The Key to Successful CeramicRestoration, Quintessence Publishing Co., Inc., Chicago (1995). However,more than the difference of value describes the subtlety of colors ofhuman teeth. In addition, the majority of dentists cannot afford tofabricate individual plastic facets or porcelain chips or tabs each timethey are needed. There have also been attempts to modify the shadeguides by “staining” them. While this may be of some benefit in matchingcolor, it cannot include value.

[0007] Other methods to describe the range of colors in human teeth usephotographs, slides, or drawings with accompanying description of colorsand, in recent years, computer images via the Internet. These methodsare limited because the images are influenced by many different factorssuch as the quality of films, monitors, or cameras. For example, thesame image of a tooth viewed on one type of monitor may be differentfrom that when viewed on a different monitor.

[0008] Photometers, spectrophotometers, and various digitized andcomputerized devices have also been introduced to analyze andcommunicate the color of teeth. Many of these devices are not perfectedas yet, and are not practical for the majority of dental professionalsbecause of their cost and/or complexity. Furthermore, even when usingthese electronic devices, the analyses are still described andcommunicated in letters, numbers, or both, rather than in color.

[0009] There is thus a need for a method to communicate color that iseconomical, accurate, amenable to use for more than one patient, andeasy to use in a dental office.

SUMMARY OF THE INVENTION

[0010] The invention is directed to a system, and a method of using thesystem, of a plurality of translucent films having color distributionsand/or shades of color found in human teeth, which are used to conveythese color distributions among dental professionals and patients. It isunderstood for this invention that color encompasses both color and thevarious shades of a particular color. The films may be reversiblyself-adhesive for placement or alignment on a template, or on top ofanother film, until the desired or matching color is achieved. The colorto be matched may be that of the entire tooth, or only a section of thetooth. This sequence of films, providing the desired color for each areaof the tooth, is conveyed among dental professionals and patients byindicia for the colors. In this way, the system allows the precise, orclosely approximated, colors for the areas to be communicated.Subsequently, a dental prosthesis can be made having colors that closelyapproximate all areas of a patient's natural tooth, relative to eitherthe tooth or to commercial shade guides.

[0011] In one embodiment, the system contains a series of thesetranslucent films in a plurality of the colors found in human teeth. Inanother embodiment, the colors match those of dental porcelain powdersthat are used in preparing dental prostheses. The films may be in avariety of sizes and shapes, and may also have divisions correspondingto different parts or areas of the tooth.

[0012] The invention will be further appreciated in light of thefollowing drawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 illustrates three divisions of a tooth.

[0014]FIG. 2 illustrates six divisions of a tooth.

[0015]FIG. 3 illustrates the positioning of films on a template.

DETAILED DESCRIPTION

[0016] A system is disclosed for closely approximating the colors,and/or shades of colors, of a dental prosthesis to that of a naturaltooth, and communicating these colors to dental professionals using aseries of colored, translucent films so that the color of the prosthesismore closely approximates that of the natural tooth. The use of colorencompasses the description of color and color shades that is known toone skilled in the art. This includes, and is not limited to,descriptive terms such as chroma, hue, and value. In one embodiment, thefilms are removably self-adhering. In another embodiment, the films areremovably partially self-adhering. In yet another embodiment, the filmsare non-self-adhering. The films comprise a system, indicating thenumerous colors and shades of color found in a tooth and used indifferent dental porcelain systems to approximate colors in part of atooth or in the entire tooth. Any dental prosthesis, such as a crown, abridge, a denture, a partial denture, etc., may be made usinginformation provided by the inventive system. Thus, the system may beused as a color guide or a shade guide by itself.

[0017] In producing the films, custom porcelain shade guides areprepared from porcelain powders in a range of colors found in teeth. Inrecent years, dental porcelain makers have produced powders of a numberof different colors which are commonly found in human teeth. Forexample, the Creative Color System of Degussa porcelain (Degussa-NeyDental Inc., Bloomfield, Conn.) includes twenty-six different shades, inaddition to the regular sixteen dentin colors, four incisal colors, andsixteen opaque colors. The Creation porcelain system produced by WillieGeller (Dental Systems Group, Utica, N.Y.) consists of fifty-nineshades, in addition to the regular sixteen dentin colors, four incisalcolors, and sixteen opaque colors.

[0018] Porcelain shade guides are a series of tabs or chips, often inthe shape of a tooth, and have a thickness of about one-half millimeter.Other types of shade guides may also be used, for example, paper shadeguides such as used to show colors of paint. The colors of each of thesechips or shade guides are measured, and then inks that match the colorsare printed on a series of translucent films. Variations of these colorsare also made, for example, using the method of dilution as described byMuia in The Four Dimensional Tooth Color System (Quintessence PublishingCo., Inc., Chicago, 1985), the relevant sections of which are expresslyincorporated by reference herein in their entirety. This ensures thatthe inventive shading system encompasses the often subtle differences incolor between the porcelain chip, or paper shade guide, and that of anatural tooth.

[0019] The colors of the custom or commercially available porcelainshade guides that are prepared from porcelain powders are measured sothat a printing ink may be prepared with the precise matching color.Measurement can be done using a spectrophotometer or other type ofinstrument that expresses colors numerically, as is known to one skilledin the art. For example, a procedure using a spectrophotometer and theassociated mathematical calculations for the numerical expression ofcolor is described in A Guide to Understanding Color Communication(Monograph L10-001, 1/2000, X-Rite, Incorporated, Grandville, Mich.)which is expressly incorporated by reference herein in its entirety.Briefly, the spectrophotometer measures spectral data, such as theamount of light reflected from an object, at several intervals along thevisible spectrum and represents these data as a spectral curve. The dataare mathematically transformed into standardized colorimetric terms,which can be used with various color scales for assessment. Asrecommended by the Commission Internationale de l'Eclairage, twoalternate color scales may be used for this assessment. These scales arethe CIE 1976 (L*a*b*) or CIELAB scale, and the CIELCH scale (L*C*h⁰)where L* defines lightness, a* denotes the red/green value, b* denotesthe yellow/blue value, C* specifies chroma, and h⁰ denotes hue angle,which is an angular measurement. As described in the monograph, thesevalues are used to calculate a color in a color space using eitherCartesian coordinates or polar coordinates in order to accurately definethe color.

[0020] Using the color assessment derived from these scales, coloredprinting inks are prepared having the same color assessment as theporcelain chips or shade guides. An example of colored inks that can beused for printing the translucent films is the Syntex Pantone Series,supplied by Kohl & Madden (Fort Lee, N.J.). The colored ink is thencopied or printed onto each of a series of translucent films, usingmethods known to one skilled in the art. The films are commerciallyavailable and are made from various polymers. The translucent nature ofthe films allows them to simulate the translucent appearance of toothenamel. An example of a film that may be used is Fasson® CRACK'N PEEL®700 clear polyester, made by Avery Dennison Corporation (GraphicsDivision, Painesville, Ohio). These films may be self-adhering,partially self-adhering, non self-adhering, and combinations thereof,and have a thickness from about 1 mil to about 2 mil. To ensure thenumerical assessment of color match, the color of the printed film maybe quantitated, as previously described.

[0021] A dental professional can produce almost every different colorfound in human teeth using the method previously described. The methodof making the inventive films is based upon custom shade tabs or chipsto match different levels of color, or color mixes, that are found inhuman teeth by systematically diluting colors represented in existingporcelain systems and porcelain powders to different shades of colors.Almost a limitless number of shades of colors can be produced from anyporcelain system using this approach.

[0022] The dimensions of color are described by Hegenbarth in CreativeCeramic Color: A Practical System (Quintessence Publishing Co., Inc1989, Chicago) which is expressly incorporated by reference herein inits entirety. To understand color mixes they must be separated intotheir three principal properties: hue (color tone), value (colorbrightness), and chroma (color saturation). What are usually called“colors”, such as red, green, blue, yellow, etc. are more preciselytermed hues, although the more common term “color” is used in describingthe inventive system. While hues may be intensified or diluted, theycannot be changed into other colors unless they are mixed with anotherhue.

[0023] The value, or brightness of a color, describes how much light ofa particular color is reflected or absorbed by an object, or the pointit takes on a gray scale between black and white. One way ofunderstanding value is by the relationship between the object and itsdistance from a light source. If the object is nearer the light source,it appears brighter; if it is further away, it appears darker.

[0024] Chroma, or color saturation, describes the strength of purity ofa particular hue. For transparent or translucent substances, such asenamel of teeth or baked dental porcelain powders, chroma depends on thethickness of the material. The thicker the substance, the more intensethe effect of the color. This is also one source of the problemsassociated with the use of present shade guides to convey color: toachieve the color intensity of a conventional shade guide, the thicknessof the porcelain layers must either be increased beyond clinicalstandards, or must be strengthened by the addition of intense colormodifiers.

[0025] The inventive apparatus and method provide an array and form ofreproducing these subtle colors of various porcelain systems, as well astheir intensities and characterizations, in order to more closelyapproximate the colors of a human tooth, and to communicate these colorsamong dental professional and patients. Examples of such intensities andcharacterizations are found in Vanbini and Mangani, Practical Proceduresand Aesthetic Dentistry (2001), 13, pp. 19-26, which is expresslyincorporated by reference herein in its entirety. The inventive systemprovides a way to determine, and convey to a dental professional, theprecise sequence and areas of films that will yield a dental prosthesisthat most closely approximates the hue, chroma, and value, of the partsof the natural tooth or teeth that are being replaced.

[0026] In another embodiment, the invention provides a method todetermine and communicate the patterns of opalescence on a tooth, whichis due to the reflection of iridescent light by the tooth. The toothenamel, due to its translucent character, is responsible for theopalescence of natural teeth. Enamel has the capacity to enhance theshort wavelength component of the spectrum of light that it encounters,thus rendering life to the blue-gray shades that are evident at theincisal halo area of the tooth. Five common types of opalescence havebeen described by Vanbini and Mangani. In type 1, mamelon-like, the halofollows the incisal outline of the mamelon of the dentin body. Type 2,split mamelons, presents itself with a large mamelon divided by anaccessory vertical groove. In type 3, comb-like, there are many smallvertical grooves that create a “comb-like” halo. Type 4, window-like,presents itself as a regular halo that creates a narrow “window” betweenthe dentin body and incisal margin. In type 5, stain-like, the halo isan amber stain that rises from the incisal margin towards thecoronal/middle third in the shape of a triangle. These blue-gray shadepatterns may be printed on translucent films, and sections of the filmthat contain the pattern may subsequently be placed on a template, orlayered on another film, to match that found on the natural tooth.

[0027] In another embodiment, the common patterns of hypo-calcificationin human teeth, as also described by Vanbini and Mangani, can beconveyed by printing films with various white patterns that resemblehypocalcifications. Hypocalcified areas of the tooth are presented asdot like, and occasionally irregular, opaque, intense, milky whitestains that are found in various areas of the tooth. The patterns in theenamel can appear as small, round white areas, small clouds, small whitespots that are distributed in a uniform way, and/or white spots that arearranged in a horizontal band. A film, or a section of a film, that hasthe desired hypocalcifications pattern, may be placed on a template orlayered on top of another film to obtain the desired effect.

[0028] In still another embodiment, the films include colors to indicatethe value of a tooth, that is, its translucent grayness. One or more ofthese films are overlaid on the sequence of films that has matched thetooth color (more specifically, hue and chroma) to approximate thevalue. This advantageously eliminates the need for the dentalprofessional to rely on costly plastic or porcelain facets to indicatevalue.

[0029] The series of translucent films, having one or more of thepreviously described representations of hue, chroma, value, opalescence,translucence, and hypocalcifications, may be configured in any shape.For example, the films may be shaped as squares, rectangles, triangles,or tooth-like structures. They may be cut into the shape of shade tabsor other models, or small sections.

[0030] To meet the need of approximating the complex shade patterns ofhuman teeth, the films are layered or placed in a pattern or order thatmost closely approximates the desired color. This may be accomplished byplacing the films on any sort of two dimensional or three-dimensionaltemplates, such as a model tooth, a commercial color guide, or a coloredphotograph, until the colors match the tooth to the satisfaction of thedental professional and/or patient.

[0031] The films may or may not be divided into the shape of thesection, or part, of the tooth to be matched. If divided, any number ofdivisions may be used. For example, as shown in FIG. 1, a film 10, whichmay be in a shape generally representing a tooth, may be divided intothree parts: cervical 15, middle 20, and incisal 25 to represent partsof a tooth. In another example, as shown in FIG. 2, the films may alsobe further divided equally at the middle from cervical to incisal tomake total six parts, three on a mesial surface 30, 40, and 50, andthree on a distal surface 35, 45, and 55. The locations of the distaland mesial surfaces of the tooth that are represented in FIG. 2 may bereversed, depending upon the tooth's location in the jaw. The distalsurface of the tooth is that which is farthest from the middle of thefront jaw; the mesial surface is that which is closest to the middle ofthe front jaw. The films may also be cut into smaller sections andshapes, as desired by the dental professional. Alternatively, the filmsmay have no divisions.

[0032] The divisions on the film corresponding to the different areas ofthe tooth are made as perforations, deep creases, markings, or any otherindicators that allow the dental professional to easily remove a desiredsection from the rest of the film and place the section onto a template.The films themselves may also be of various sizes that can be furtherconfigured at the discretion of the dental professional to obtain thedesired shade or shades of color of the particular tooth area or surfacethat is being matched.

[0033] In another embodiment, the individual films are removablyself-adhesive. As shown in FIG. 3, the film 12 a can be pressed onto theappropriate area of a shade tab of one of the dental shade guidesystems, or on another appropriate type of template 60, using aconvenient means or technique, such as with fingers, forceps, or otherappropriate devices. Once a section of film is placed on a template, asection of a film 12 b of the same or a different color may be placedeither partially or completely under or on top of it to more closelyapproximate the natural tooth color. To obtain an even more accuratematch for the color of different areas of the dental prosthesis, thefilms may be configured into smaller pieces and/or shapes, and anynumber of films may be layered until the desired color is obtained onthe final film/template assembly 65. A film, or section of film, mayalso be removed and replaced with another colored film.

[0034] In an additional embodiment, each film bears an indicium whichidentify or codes its matching composition and color in a custom orcommercial shade guide system, such as a porcelain shade guide system.The indicium may be further described, either on the film itself, and/orin an index accompanying the film system. Such codes facilitatecommunication between various dental professionals and minimizessubjective interpretations. For example, a dental professional can senda technician a modified template containing the films, with the indexedsections of film corresponding to the tooth area(s) precisely defined,or just the desired codes for the films, with reference to the index.Alternatively, the dental professional can simply describe on a toothdiagram, which may be either a hard copy or via software, the indexnumbers of the films used on various sections of the template to obtainthe desired colors. A dental technician can reproduce the same colorsusing his or her own template, if desired, and verify, clarify, orquestion the matching before beginning work, if necessary.

[0035] In other embodiments, the films, may be packaged, or formed, asmultiple strips or sheets. These may be of any desired size, and may beorganized, for example, in a reversibly bound or perforated booklet, abundle, a wheel, a palette, or in any other type of format for ease inselection and use. Any other packaging or organizing system may also beemployed. Dental professionals may also use the various sizes and shapesof the films to experiment with various colors. This allowsvisualization of the desired color or shade and facilitates comparisonsto the resulting color of baked porcelain mixtures.

[0036] In yet another embodiment, the films may be used to match thecolors of a tooth or teeth that are shown or printed on other types offilms, photographs, computer generated models, digitized photographicmodels, and the like.

[0037] It should be understood that the embodiments of the presentinvention shown and described in the specification are only preferredembodiments of the inventor who is skilled in the art and are notlimiting in any way. For example, the invention may be used inveterinary practice to convey tooth color of a nonhuman animal. Foranother example, the invention may be used in cosmetic dentistry toapproximate a color other than that of a natural tooth, for example, forpatients wishing to have a prosthesis that is “whiter” than theirnatural tooth, that lacks the hypocalcifications found in their naturaltooth, etc. Therefore, various changes, modifications or alterations tothese embodiments may be made or resorted to without departing from thespirit of the invention and the scope of the following claims.

What is claimed is:
 1. A system to approximate a distribution of atleast one color property in a tooth, said system comprising a pluralityof colored, translucent films, each of said films having at least onecolor property found in a tooth and having indicium for said colorproperty.
 2. The system of claim 1 wherein said films are selected fromthe group consisting of self-adhering films, partially self-adheringfilms, non-self-adhering, and combinations thereof.
 3. The system ofclaim 1 wherein said color property is selected from the groupconsisting of chroma, hue, value, opalescence, hypocalcifications, andcombinations thereof.
 4. The system of claim 1 wherein said filmscontain dividers selected from the group consisting of perforations,creases, markings, and combinations thereof.
 5. The system of claim 1wherein said films are organized in a form selected from the groupconsisting of a bundle, a booklet, a wheel, and a palette.
 6. The systemof claim 1 wherein said films have a shape selected from the groupconsisting of strips, circles, rectangles, triangles, tooth-shaped,squares, sheets, and combinations thereof.
 7. A dental color system thatapproximates at least one color of a tooth comprising a plurality ofcolored translucent films, each of said films having an indicium forsaid color.
 8. The system of claim 7 wherein said indicium indicates adental porcelain powder color.
 9. The system of claim 7 wherein saiddental porcelain powder color is printed on said films.
 10. The systemof claim 7 wherein said indicium is selected from the group consistingof bar codes, letters, numbers, and combinations thereof.
 11. A methodto convey color distribution in at least one tooth area to a dentalprofessional comprising providing a plurality of translucent films in aplurality of colors capable of layering to achieve a color approximatingthat of a tooth area, the films having an indicium for the color,layering the films to approximate color of the area of the tooth,determining the indicium for the layered films, conveying the indiciumto a dental professional to approximate the color of the tooth area. 12.The method of claim 11 wherein the layered films comprise film sequenceand tooth area.
 13. The method of claim 11 wherein the films are layeredon a template.
 14. The method of claim 11 wherein the films are printedor copied with inks in a plurality of colors assessed from a dentalcolor scale.
 15. A tooth color approximating apparatus comprising aplurality of translucent films, each of said films printed with a colorthat, in layered sequence order, is capable of approximating at leastone of hue, chroma, or value of a tooth, and instructions for use. 16.The apparatus of claim 15 further comprising indicium for conveying thelayered sequence.
 17. The apparatus of claim 15 further comprising atemplate for locating an area of the tooth for color approximation.